pester power
n. The ability children have to nag their parents into purchasing items they would otherwise not buy or performing actions they would otherwise not do.
Nine out of every 10 pupils questioned claimed they wanted to learn about energy efficiency in schools. The centre adds that a key benefit from encouraging pupils to tackle the issue is the wider impact their new understanding appears to have in the community. Children are using their pester power to turn school learning into positive energy-efficiency habits at home.
—Jerome Monahan, “A new generation,” The Guardian, January 29, 2002
1979 (earliest)
At a press conference here yesterday, ACT released its new 22-minute film examining the state of commercial children's television, "Kids for Sale." … Portions of the movie deal with the mission of advertising for children: to get their parents to buy a certain type of toy or cereal. "They (the children) use all the pester power they can muster" to talk their parents into purchases, a narrator warned.
—Larry Kramer, “Kids Advertising Hearings to Open,” The Washington Post, February 28, 1979